Interesting, as this image caught my attention first - assuming you mean this one -
http://www.flickr.com/photos/m_speer/3124485094/ it has a certain comedy about it, if the wing was there I think it would have been just another picture of a gull. As it is, I like the shapes and the tonality.
That's the one. As folks here are pretty-well aware, I'm happy to go into more depth about my opinions on just about any subject
Please be aware, I'm not challenging the fact that you like it, or the validity of your opinion against mine- I'm enhancing my explanation of why I don't like it and why you may- which is a different thing altogether. Art is very subjective, and appreciation is in the eye of the beholder.
The negative space is wasted, there's no value to it compared to the gull (though that changes a lot with a clockwise rotation for a Western we-write-left-to-right-and-top-to-bottom viewer.)
You don't get the gull's eye, so in general (again that whole break the rules once you understand them) it's not a good live subject picture because you as the viewer aren't interacting with the subject eye-to-eye.
Your eye is immediately drawn to the brightest point, then it slides down to the corner and out of the (badly vignetted) frame. All the interesting detail is on the more-properly exposed wing, where we don't even get to see the contrast of the black end-feathers on the truncated wing.
The feet are cut off- the tail's cut off, the face is blown out, we can't look into the eye and connect- the sum of all of that is poor- each on its own isn't bad, but the combo isn't good.
The shapes don't lead anywhere, and don't do the whole tension-release thing that the hoity-toity art crowd talks about. The tonal range of the bird's left wing is good, but we're not lead there and we have to deal with massively blown highlights in the middle and muddy chopped-off feet on the bottom.
I think your mind is more entertained by "I didn't figure this out immediately because it's a strange angle and crop" rather than "that's a great shot!" (Please note that I'm painting you with the broader brush of the funky angle appreciation society.) I think if we had more bird and an eye, we'd have more in common in terms of "good shottedness." If the lighting drew my eye into the picture instead of starting there and drawing it away, we may also have more in common in our appreciation.
Great birds shots are difficult, because you can't really light the bird, you can't really choose the angle, especially if they're in flight and you definitely don't get time to frame for flight shots. But in my mind, a great shot should be a great shot, no qualifiers allowed or necessary.
So there you have it- most of how I formed my opinion with a dash of how I formed my opinion of your opinion added not to attempt to devalue or demean your opinion, just to try to resolve the differences in what we see.
Oh- one other thing for the OP to use to evaluate things- I generally hang new pictures up at 8x10 by my door. Every time I go in and out for the first week, I try to notice the picture. Sometimes by studying it, sometimes by glancing at it. Stuff that makes it past the "should I print it test" followed by the "how is it by the door test" generally finds its way into the prints I'll sell. Occasionally, a picture makes it to that point without all the tests for various reasons- even after all that, some things just don't inspire people the way they do me. Don't sweat that- if you like it, that's the primary thing, what other people tell you should be secondary to that unless you're shooting for or selling to them, where it may "impact your artistic sensibilities."
As an example, the Bald Eagle that's my avatar is a fully-body shot of an Eagle in what I find to be very interesting behavior. After a week by the door, I was still interested in the behavior and the feather detail, but I could see it simply didn't work as a shot to sell. I still have it as a shot on a wall, I still like the shot, I still haven't sold a copy.
I seriously hope the folks who've found value in my comments do spend the time to Google around a bit, the two toughest things to learn to do well in photography are composition and lighting.
